The overall objective of the curret research effort is to study the interrelationship between (1) the ability of the mammalian stomach to maintain electrical and pH gradients, (2) reflux of upper intestinal chyme, particularly the bile acids, and (3) the development of clinical and experimental gastric mucosal disease, specifically acute post-traumatic hemorrhagic gastritis, chronic atrophic gastritis, and post-operative alkaline reflux gastritis.